[CF-metadata] Integerized Sinusoidal Grid

From: Julien Demaria <dem>
Date: Wed, 08 Mar 2006 16:03:58 +0100

Hi,

We search to describe in CF netCDF convention a "integerized sinusoidal
equal-area grid (ISIN grid)" as used in SEAWiFS/MODIS Level 3 HDF data.
Its characteristics are that on each row of latitude there is an integer
number of longitude bins. Poles always represented as 3 triangular bins.
Bins aren't aligned between rows.
In SEAWiFS/MODIS Level 3 HDF only bins (pixels) with data are stored,
and the geolocation information for each bin is only its indice in the
global integerized sinusoidal grid (first bin is on south, last on the
north).

The only mecanisms I see in CF to do that are:

- "5.3 Reduced horizontal grid": but:
               Are bins always aligned ?
        How can I know/compute the coverage of each pixel (its vertex) ?
        Is this mechanism largely used ?
        Are there free tools to see this kind of CF files ? (FERRET ?)

- "5.4 Timeseries of station data": but:
        I don't believe this mecanism is really appropriated...
        How can I know/compute the coverage of each pixel (its vertex) ?

- "5.6 Grid mappings and projections": in fact I think we can't
represent ISIN grids with that model ?


The simpliest way I see is:

"
dimensions:
         Data_Bins = 5965 ;
variables:
         int bin_num(Data_Bins) ;
                 bin_num:long_name = "Index number of each bin in the
global sinusoidal grid" ;
         short mean(Data_Bins) ;
                 mean:long_name = "Arithmetic mean of the geophysical
variable for each bin" ;
                mean:units = "mg.m-3" ;

// global attributes:
                 :Conventions = "CF-1.0" ;
                :Parameter_Code = "CHL1" ;
                :Parameter = "Chlorophyll A - case 1 water" ;
"

It is compliant with the CF checker..., but are there any tool who can
use these files ?



Many Thanks in advance for help,

Julien
Received on Wed Mar 08 2006 - 08:03:58 GMT